UUEncode is a way to convert binary data to a format where only readable
chars are used. That means only ASCII chars (char-codes 32 to 126), and
not even all of them. This way the (binary) file can be send over
ASCII-only lines (like some, now older, "internets") without being crippled
..

a TAR-file is something that comes outof the UNIX world. It's short for
TApe aRchive. It's supposed to be a backup of disk-data to magnetic tape.
Sort of equivalent of ARJ.